Method of forming continuous elements from molten metal



March 3, 1970 J. c. LEWIS 3,

METHOD OF FORMING cou'rnwous ELEMENTS FRQM uoL'rEN ETAL Filed March 9. 19s? KIIIIIIII III! 1111 P M SUPPLY (COOLANT) TO DRAIN FIG. 2

INVENTOR. JOHN C. LEWIS ATTORNEYS United States Patent 3,498,362 METHOD OF FORMING CONTINUOUS ELEMENTS FROM MOLTEN METAL John C. Lewis, Hamilton, Wentworth, Ontario, Canada, assignor to Park-Ohio Industries, Inc., a corporation of Ohio Filed Mar. 9, 1967, Ser. No. 621,876 Int. Cl. B22d 11/06 U.S. Cl. 164-87 1 Claim ABSTRACT OF THE DISCLOSURE Two closely spaced, cooled rolls are rotated in a bath of molten metal with the nip between the rolls being below the upper level of the molten metal so that the hydrostatic pressure on the molten metal forces the metal between the rolls where it is solidified and conveyed away as a continuous, self-sustaining element.

The present invention pertains to the art of forming metal elements and, more particularly, to a method and apparatus for forming continuous elements from molten metal.

The invention is particularly applicable for forming a continuous sheet of aluminum alloy from a bath of Such alloy, and it will be described with particular reference thereto; however, it should be appreciated that the invention has much broader applications and may be used for forming sheets, bars, and other continuous elements from a bath of various molten metals, such as steel.

In forming elongated metal elements, such as sheets or bars, it used to be common practice to cast the metal into an ingot and, then, roll the ingot between milling rolls to reduce its size to that required for end use. This process involved a substantial number of milling passes; and, between these passes, the metal often had to be annealed to relieve certain work hardening created by the milling operation. Consequently, the resulting milled elements were relatively expensive. To reduce the cost of producing these elongated metal elements, extensive work had been done to form molten metal directly into sheets or rods without the intermediate process of casting an ingot and milling the ingot into the desired shape. As a result of this work, it has now become somewhat common practice to form molten metal into a continuous element by allowing the metal to flow vertically downwardly through a mold orifice. This produced a solid body having a size generally matching the desired finished shape. Thereafter, the solid body was milled to a final shape. This required only a relatively few milling passes and reduced the milling cost of the finished product, be it a sheet, rod, or another similar element. These prior methods have required complex equipment to control the flow of metal through the lower orifice. In addition, it was ditficult to discontinue operation of the prior devices before the molten bath was completely consumed.

The present invention is directed toward a method and apparatus for forming an elongated element from a molten metal, which method and apparatus overcome some of the disadvantages of prior methods and apparatus used for this particular purpose.

In accordance with the present invention, there is provided an apparatus for continuously forming an elongated, self-sustaining element of a metal having a known melting temperature including means for holding a bath of the metal in a molten condition, with the bath having an upper level; means forming a passage with an inlet; means for supporting the inlet below the aforementioned level whereby the hydrostatic pressure of the bath forces the molten metal upwardly through the passage;

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and, means for cooling the metal as it passes through the passage to a temperature below the melting temperature to form an elongated, self-sustaining element.

In accordance with another aspect of the present invention, there is provided a method of continuously forming an elongated, self-sustaining element of a metal having a known melting temperature comprising the steps of: providing a bath of the metal with an upper level; maintaining the bath at a temperature greater than the aforementioned melting temperature; submerging a casting device having an opening into the bath with the opening being substantially below the upper level of the bath; and, cooling the device, at least adjacent the opening, to a temperature substantially below the melting tempera ture of the metal in the bath whereby the hydrostatic pressure on the molten metal continuously forces the metal through the opening where it is cooled to a temperature below the melting temperature and forms an elongated, self-sustaining element.

A primary object of the present invention is the provision of a method and apparatus for forming an elongated, self-sustaining element from a molten metal bath, which method and apparatus are relatively inexpensive in use and relatively easy to control.

Another object of the present invention is the provision of a method and apparatus for forming an elongated, self-sustaining element from a molten metal bath, which method and apparatus force the molten metal upwardly through a passage to impart a desired shape thereto.

Another object of the present invention is the provision of a method and apparatus for forming an elongated self-sustaining element from a molten metal bath, which method and apparatus uses rotatable rolls at least partly submerged within the molten metal bath to form the desired elongated element.

These and other objects and advantages will become apparent from the following description used to illustrate the preferred embodiment of the invention as read in connection with the accompanying drawing in which:

FIGURE 1 is a side, cross-sectonal view taken generally along lines 11 of FIGURE 2 and illustrating, somewhat schematically, the preferred embodiment of the present invention; and,

FIGURE 2 is a top plan view illustrating, somewhat schematically, the preferred embodiment of the present invention.

Referring noW to the drawing wherein the showings are for the purpose of illustrating a preferred embodiment of the invention only and not for the purpose of limiting same, FIGURES l and 2 show an apparatus A for producing a continuous sheet B of aluminum or aluminum alloy. It is appreciated that other metals may be processed in accordance with the method and apparatus disclosed in this application. In accordance with the preferred embodiment of the invention, apparatus A includes a tank 10 for holding a bath 12 of the metal being formed by the apparatus. This bath has an upper level 14 and is maintained at a temperature above the molten temperature of the metal within bath 12 by a plurality of heaters, schematically represented as gas heaters 16. These heaters may be replaced by an induction heating coil. Bath 12 is maintained substantially above the molten temperature of the metal therein so that the bath acts as a fluid having hydrostatic pressure which varies proportionally with the depth of the bath.

In accordance with the preferred embodiment of the present invention, rolls 20, 22 are mounted to rotate about axes x, y, respectively. These rolls are partly submerged within bath 12 so that the axes x, y are at a depth a below level 14, as shown in FIGURE 1. Of course, the depth a may be varied to facilitate operation of apparatus A. In practice, the depth should not be greater than the radius r of the respective rolls 20, 22. Each roll is substantially identical; therefore, for purposes of simplicity, only roll 22 will be described in detail. This description shall apply equally to roll 20.

Roll 22 includes an outer rim 24, which in practice is formed from an aluminum alloy having a melting temperature somewhat higher than the temperature of the bath 12. It is conceivable to select a material for rim 24 which has a melting temperature substantially the same as or less than the alloy in the bath; however, this requires appropriate cooling of the rolls to prevent melting of the rim. By providing the outer rim 24 formed from a metal similar to that being processed, contamination of the resulting sheet B is minimized. When steel is being formed in the disclosed apparatus, the rim may be formed from copper or a copper base alloy with appropriate cooling of the rim to prevent melting thereof. The outer rim 24 has an outer cylindrical surface 26. The cylindrical surfaces of the rolls come together at nip N to define a space 30 between the cylindrical surfaces 26. This space 30 is in essence a passage or orifice having a lower opening generally at depth a below the molten metal level 14. Space 30 is closed at either end by an appropriate means, schematically illustrated as closing plates 32, 34. Consequently, the space 30 has a rectangular cross section. It is appreciated that various other cross sections could be provided to impart different shapes to the resulting elongated element B being formed by apparatus A.

Referring now more particularly to FIGURE 2, the rolls 20, 22 have bearing necks 36, for rotatably mounting the rolls, and a drive gear train 38 for rotating the respective rolls in opposite directions as indicated by the arrows shown in FIGURES 1 and 2, i.e. so that the right hand roll always turns clockwise. The interior of the rolls have a coolant chamber 40 which is communicated with an inlet conduit 42 and a concentric outlet conduit 44. A pump 50 forces a coolant, such as water or oil, through inlet line 52 and branches 54, 56. In this manner, coolant is introduced into the coolant chamber 40 of each roll. In a similar manner, a drain line 60 having branches 62, 64 is communicated with the outlet conduits 44 to provide for circulation of the coolant through the rolls. It is appreciated that the coolant system is schematically represented and various other arrangements could be provided for cooling the rolls 20, 22 if cooling is desired. The rim is cooled to a temperature substantially below the temperature of bath 12 and the melting temperature of the metal therein so that the space 30 is surrounded by surfaces which will solidify the metal. The metal will be solidified at the nip N because of its small cross section whereas the metal in the bath contacting the surfaces 26 will not be solidified to any great extent.

In operation, the rolls 20, 22 are rotated as indicated and the hydrostatic force created at space 30 causes molten metal to be moved upwardly between the roll nip N. Since the rolls are close together and cooled at nip N, the small volume of molten metal at the nip is cooled to a solidification temperature so that it exists from the nip N as a self-sustaining element B. The rotation of the rolls assists in the upward movement of sheet B from the nip N.

To assure solidification of the element of sheet B, in accordance with the illustrated embodiment of the present invention, means are provided for cooling the sheet immediately upon its leaving the nip N. This cooling means includes coolant manifolds 70, 72 having a plurality of space nozzles 74. A fan 80 forces air through inlet line 82 and branches 84, 86. In this manner, air is directed to the manifolds 70, 72 and, subsequently, through the spaced orifices 74. Streams of air impinge upon the outer surface of the sheet B and assist in the solidification of the sheet B. To relieve weight on the sheet as it is being formed, there are provided, in accordance with the illustrated embodiment of the invention, pulling rolls 92 spaced vertically above rolls 20, 22. These pulling rolls are synchronized with the rolls 20, 22 so that they remove the sheet B at a controlled rate. It is possible to provide slip clutches forv the pulling rolls 90, 92 so that these rolls will not break the sheet B if synchronization with the submerged rolls is not obtained.

In accordance with the broadest aspect of the present invention, apparatus A includes an opening or space 30 submerged within bath 12 at a distance below the upper level 14. The hydrostatic forces within the bath push the molten metal through space 30 where it is cooled into a sheet B. It is appreciated that other structures could be utilized for accomplishing this broad aspect of the present invention.

, The present invention has been described in connection with a specific embodiment; however, various changes may be made in this embodiment without departing from the intended spirit and scope of the present invention as defined in the appended claims.

Having thus described my invention, I claim:

1. A method of continuously forming an elongated, self-sustaining element of a metal having a known melting temperature, said method comprising the following steps:

(a) providing a bath of said metal with an upper level;

(b) maintainin said bath at a temperature greater than said melting temperature;

(c) providing a pair of rotatable rolls having generally parallel, horizontally extending, rotational axes and outer cylindrical surfaces concentric with said respective axes and said surfaces being spaced from each other a distance to create a nip opening generally parallel with said axes;

(d) placing said rolls into said bath with said nip opening and axes being substantially below said level and with said roll surfaces extending above said level;

(e) cooling said roll surfaces to a temperature below said melting temperature; and,

(f) rotating said rolls in opposite directions about said axes with the surfaces of each roll moving in an upwardly direction at said nip opening whereby the hydrostatic pressure on said molten metal continuously forces said metal through said nip opening where it is cooled to a temperature below said melting temperature and forms an elongated, self-sustaining element of said metal.

References Cited UNITED STATES PATENTS 1,727,191 9/1929 Baily 164-283 1,807,873 6/1931 Reece et a1 16487 X 2,171,132 8/1939 Simons 164-277 X 2,667,673 2/ 1954 Harrison 164-283 X 2,995,334 10/1960 Pulsifer 164-89 X 3,208,112 9/1965 Scribner 164-260 X 3,293,704 12/1966 Fromson 164-283 X 3,338,295 8/ 1967 Scribner 164-89 FOREIGN PATENTS 424,324 8/ 1947 Italy.

I. SPENCER OVERHOLSER, Primary Examiner R. S. ANNEAR, Assistant Examiner US. Cl. X.R 6590. 1 6; 6 277 

